A process for the reduction of the emission of sulphur dioxide and/or of oxides of nitrogen in the case of combustion processes by the addition of an additive based on hydrated calcium cyanamide, optionally in admixture with further reactive calcium compounds, into a combustion chamber is described in Federal Republic of Germany Offenlegungsschrift No. 38 23 848.
Published Federal Republic of Germany Patent Specification No. 29 26 107 describes a process for the separation of nitrogen oxides and possibly of halogens, sulphur and/or halogen compounds from gases in which the gases are passed, in the presence of water, over a cyanamide or through a suspension or solution of the cyanamide at a temperature of from 0.degree. to 80.degree.C. and the harmful materials are separated off. Because of the high cost of the apparatus, this process could not be used technically.
Also known are processes which recommend the use of urea and lime for the non-catalytic removal of emissions of oxides of nitrogen or sulphur dioxide.